1. Field of the Invention
The invention relates generally to labeled containers and particularly to in-mold labeled containers and processes for producing in-mold labeled containers that limit the transmission of oxygen into the containers.
2. Description of Related Art
Methods for attaching labels to containers, including plastic containers, are known in the art. For example, methods for applying adhesive agents onto the rear surface of labels and then adhering the labels onto plastic containers are known to skilled artisans. Also, in-mold labeled (IML) methods have been used for attaching labels to containers. For example, US20100001010A1 discloses an in-mold labeled container and molding process for making the container. U.S. Pat. No. 5,604,006 discloses an in-molding label process that works by adhering a label to a thermoplastic substrate in a mold cavity and injecting molten thermoplastic resin to press the label and recess it into the thermoplastic substrate. U.S. Pat. No. 4,913,643 discloses a plastic mold useful for in-mold labeling. In typical IML processes, a label is placed in a mold and then plastic is injected into the mold. The result is a plastic container with an integrated label. Plastic containers produced using IML methods can be used for a variety of purposes, e.g., a container for various foods, beverages, and the like.
Some foods and other articles need to be isolated in a container so that they do not interact with oxygen in the environment. One way to prevent such an interaction is to include an oxygen barrier in the container design. For example, Japanese Registered Utility Model No. 3024995 discloses a container wherein a label having an oxygen barrier property is bonded to a container outer wall. U.S. Pat. No. 7,608,340 discloses a container containing a layer that includes an oxygen absorbing resin containing an ethylene vinyl alcohol copolymer (EVOH) and an oxygen absorbent. Similarly, U.S. Pat. No. 7,588,157 discloses an IML container wherein a label having a barrier layer including EVOH is used to give an oxygen barrier property to the label. In addition, many products need to be packaged in a container that can be retorted during the manufacturing process.
However, the labels currently used to produce IML containers are relatively thin because the oxygen barrier layer cannot be thick if made using available methods. As a result, the oxygen barrier property of such IML containers is insufficient for keeping oxygen out of the container. Furthermore, the oxygen barrier property of these labels is adversely affected by humidity and relatively high temperatures. As a result, known IML containers made using these labels cannot be used when the products must be retorted. There is, therefore, need for new IML containers that have good oxygen barrier properties and that can be retorted if needed.